In the past, 40-inch (″) class TVs were prevalent, but many consumers now purchase 50″ class TVs and even 60″ class TVs. While the size competition was over, resolution competition has begun. Even a year ago, full high definition (FHD) class TVs belonged to an advanced model, but ultra HD (UHD) TVs now have been rapidly spread on the market.
Recently, the display market has evolved from large-area, high-resolution competition to color competition. For this reason, competition for the production of a display with excellent color has recently emerged.
A liquid crystal display displays an image by using optical properties of liquid crystals, wherein, since a liquid crystal panel displaying the image is a non-emissive device or not self-luminous, the liquid crystal display has a structure comprising the liquid crystal panel as well as a back-light unit which is disposed on a rear surface of the liquid crystal panel to provide light to the liquid crystal panel. Although the liquid crystal display is in the spotlight as a display device used in mobile devices, computer monitors, and high-definition televisions (HDTVs), the liquid crystal display is somewhat inferior to other types of displays in terms of color.
Recently, the employment of a red phosphor comprising a K—Si—F-based phosphors in a light emitting device package is most actively tried among various solutions suggested for realizing a high-quality color reproduction display (see Korean Laid-open Patent Publication No. 2015-0082426 and Japanese Laid-open Patent Publication No. 2010-93132). However, under the circumstances that a picture quality standard has been changed for UHD broadcast, a color reproduction level achievable by the application of the K—Si—F-based phosphors in the light emitting device package is insufficient for the new standard.
Thus, there is a need to develop a new technique which may dramatically improve a color gamut of a conventional LCD to the level of the new standard.